RE: datafile permissions

  • From: "Khemmanivanh, Somckit" <somckit.khemmanivanh@xxxxxxxxxxxxxxxx>
  • To: "Sinardy" <all_about_oracle@xxxxxxxxxx>, <raja4list@xxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 5 Jul 2005 22:47:33 -0700

Right, I see what you're saying. I guess to mitigate that you could
script the chmod command.
 
Personally, I don't see the need to take "downtime" for this type of
activity. I guess everyone has their own comfort levels though...
 

Thanks! 

 

________________________________

From: Sinardy [mailto:all_about_oracle@xxxxxxxxxx] 
Sent: Tuesday, July 05, 2005 10:46 PM
To: Khemmanivanh, Somckit; raja4list@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: Re: datafile permissions


Your test is good, just if you "accidentally" chmod 000 *.dbf during
online and batch job is still running what will happen to the db? 
This is what I believe his manager try to prevent.
Anyway technically you are right.
 

        ----- Original Message ----- 
        From: Khemmanivanh, Somckit
<mailto:somckit.khemmanivanh@xxxxxxxxxxxxxxxx>  
        To: all_about_oracle@xxxxxxxxxx ; raja4list@xxxxxxxxx ;
oracle-l@xxxxxxxxxxxxx 
        Sent: Wednesday, July 06, 2005 1:30 PM
        Subject: RE: datafile permissions

         
        Not to harp on this too much but I'm really failing to see how
this is such a risky task? He's going from mode 600 to 640.
         
        You can run this test yourself to see that there shouldn't be
any issues with doing this.
         
        1) create a test file
        rm skf
        touch skf
        chmod 600 skf
        ll skf
        -rw-------     0 Jul  5 22:16 skf
        
        2) As a control run the supplied C program I whipped up to test.
All it does is open the file and write a bunch text to it
         
         
        It will create a file exactly 99999999 bytes in size
         
        ll skf
        -rw-------        99999999 Jul  5 22:17 skf
        
        Below is the code (compile and run it)
         
        #include <stdio.h>
        int main ()
        {
          FILE * myf;
          int counter = 0;
         
          myf = fopen ("skf","wt");
          if (myf != NULL)
          {
             while ( counter < 99999999)
             {
              fputs ("t", myf);
              counter++;
             }
          }
        }
        
        3) Delete the skf file and recreate it with mode 600 for the run
with the chmod in it.
        --Run the program in 1 session and in another session run the
following commands.
         
        ll skf; chmod 640 skf; ll skf
        -rw-------       6062080 Jul  5 22:18 skf
        ^^^--Note the mode is 600 from the first ll skf commnd
        
        
        -rw-r-----        6193152 Jul  5 22:18 skf
        ^^^--Note the mode has changed to 640 with the chmod comand
(this while the other program is still writing to the file)
         
        4) Now recheck the file after it's all complete.
        ll skf
        -rw-r-----        99999999 Jul  5 22:19 skf
        
        Does anyone see any flaws with this test???

        Thanks! 

         
        
        
________________________________

        From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Sinardy
        Sent: Tuesday, July 05, 2005 9:31 PM
        To: raja4list@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
        Subject: Re: datafile permissions
        
        
        If someone is writing to the file then you revoke the access
using OS command which is it can be done with Unix I believe your
manager forsee this will corrupt the datafile.
         
        Anyway, if I am asked to perform such harderning change, I will
request for down time. For may be 1 hour, stop applications, shutdown,
chmod, startup, switch log file, test, star application. not only
datafile offline.
         
         
        PS: I know that 640 should be ok but chmod during online is
quite a risky task.
         
        Regards,
        Sinardy

                ----- Original Message ----- 
                From: raja rao <mailto:raja4list@xxxxxxxxx>  
                To: oracle-l@xxxxxxxxxxxxx 
                Sent: Wednesday, July 06, 2005 5:19 AM
                Subject: datafile permissions

                Hi All,
                 
                Sun OS 2.9 
                oracle 9i
                 
                In what state the datafiles should be when i want to
change the OS file permissions
                from 600 to 640 
                 
                chmod 640 *.dbf
                 
                I put the tablespace offline.  is that enough?, or
should i make the datafiles offline withi
                 
                alter database datafile 'filename' offline;
                 
                I had a fight with my manager. He asked me to put the
datafiles offline using alter database.
                But Just i put the tablespace offline and did that. Just
want to make sure what is
                the right way (precautiion to be taken) for this task ?
                 
                 
                Thanks in advance,
                Raj

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